As is known in the art, manifold absolute pressure (MAP) is used to provide critical information for EGR flow delivery and EGR system monitoring for an internal combustion engine. One technique used to provide absolute pressure is by inferring such pressure, i.e. an “inferred MAP”, calculated from mass airflow sensor readings. This technique is described in U.S. Pat. No. 5,505,178, issued Apr. 9, 1996, inventors Daniel G. Brennan and U.S. Pat. No. 5,331,036, issued Jul. 26, 1994, inventors Messih et al, both assigned to the same assignee as the present invention, the entire subject matter of both such U.S. Patent Nos. being incorporated by reference.
As is also known in the art, in some systems MAP sensors are required to prove a measure of manifold absolute pressure. In such systems it may be required to detect a malfunction of such MAP sensor. One technique suggested for this purpose is to compare each MAP sensor output reading sample directly with the “inferred MAP” at a specific idle engine operating condition. The accuracy of such method, however, may be effected by noise.